189954domain: NAppears in sequencesNumber of identity trees with 3-colored nodes.at n=9A038080Integers y such that for some integer x we have uphi(x) = uphi(y) = x-y, where uphi(n) = A047994(n) is the unitary totient function: If n = Product p_i^e_i, uphi(n) = Product (p_i^e_i - 1).at n=22A067741